1. Field of the Invention
The present invention relates to an imaging apparatus, and, more particularly, to a printhead maintenance cap for an ink jet printer.
2. Description of the Related Art
In the printing arts, ink jet printers form an image on a print medium by selectively ejecting ink from one or more of a plurality of ink jet nozzles formed in a nozzle plate of an ink jet printhead. In order to maintain the printhead at an acceptable level of performance, ink jet printers typically include a maintenance station for performing scheduled maintenance operations and for providing a sealed environment for the printhead nozzle plate during periods of non-use.
One example of a maintenance station includes a movable maintenance sled including a printhead wiper and a printhead maintenance cap. The printhead wiper includes a blade edge for engaging the printhead nozzle plate to remove waste ink and contaminants that have accumulated on the printhead nozzle plate during printing. The cap is moved by the maintenance sled from a non-contact position with respect to the printhead to a contact position with respect to the printhead in an attempt to provide a sealed environment around the ink jet nozzles of the printhead.
Typically, the cap is formed as a generally rectangular structure defined by four adjoining walls that extend vertically upwardly from a base, and is made from an elastomer, with an upper portion of the four adjoining walls defining a single sealing lip. Commonly, the elastomer cap is placed over the nozzle plate of the printhead in an attempt to provide a sufficiently humid environment to avoid undesirable drying and crystallization of ink on the printhead that may plug ink jet nozzles. Such a cap attempts to form a leak-free seal between the printhead nozzles and the ambient environment. Conventionally, this has been done in one of two ways: by forcing the elastomer cap into the printhead with enough force to deform the cap around its scaling lip, or by providing a spring-loaded gimbaling mechanism behind the cap to allow the lip of the cap to xe2x80x9cfloatxe2x80x9d with the printhead. The former typically requires large forces to produce sufficient deformation to ensure a reliable seal, due to manufacturing tolerances. The latter typically requires less force, but adds a significant number of parts, thus increasing the cost and complexity of the cap mechanism.
As ink jet printing technology has evolved, the size of the ink jet printheads has been decreasing, while the size of the printhead nozzle plate containing the ink jetting nozzles and the number of ink jet nozzles in the nozzle plate has increased. As a result, the surface area on the printhead available for establishing an effective seal with the cap generally has diminished. Also, with the larger-sized nozzle plates and the advent of non-planar printhead topography in the regions surrounding the nozzle plate, it has become increasingly difficult to effect an acceptable degree of sealing around the nozzle plate.
What is needed in the art is a printhead maintenance cap having features to maintain an effective seal around the printhead nozzle plate and which may tend to reduce the amount of force required to effect capping.
The present invention provides a printhead maintenance cap having features to maintain an effective seal around the printhead nozzle plate and which may tend to reduce the amount of force required to effect capping.
The present invention, in one form thereof, is directed to a printhead maintenance cap. The printhead maintenance cap includes a base and a wall portion. The wall portion is defined by a plurality of adjoining walls, and has a proximal end and a distal end. The plurality of adjoining walls defines an interior region. The proximal end is coupled to the base. A first lip extends from the distal end of the wall portion by a first extent in a direction non-orthogonal to the base. The first lip defines a first perimetrical sealing surface. A second lip extends from the distal end of the wall portion by a second extent. The second lip is spaced apart from the first lip. The second lip defines a second perimetrical sealing surface.
In another form thereof, the present invention is directed to a printhead maintenance cap including a wall portion having a proximal end and a distal end, the wall portion defining an interior region. A first perimetrical lip extends from the distal end of the wall portion by a first extent, the first perimetrical lip defining a primary sealing surface. A second perimetrical lip extends from the distal end of the wall portion by a second extent, the second perimetrical lip being spaced apart from the first perimetrical lip, wherein a perimetrical valley is defined between the first perimetrical lip and the second perimetrical lip.
In yet another form thereof, the present invention is directed to an imaging apparatus including a printhead carrier, a printhead mounted to the printhead carrier, and a printhead maintenance station including a printhead maintenance cap and a moving mechanism coupled to the printhead maintenance cap for moving the printhead maintenance cap relative to the printhead. The printhead maintenance cap includes a base and a wall portion. The wall portion is defined by a plurality of adjoining walls, and has a proximal end and a distal end. The plurality of adjoining walls define an interior region. The proximal end is coupled to the base. A first lip extends from the distal end of the wall portion by a first extent in a direction non-orthogonal to the base, the first lip defining a first perimetrical sealing surface. A second lip extends from the distal end of the wall portion by a second extent, the second lip being spaced apart from the first lip. The second lip defines a second perimetrical sealing surface.
In still another form thereof, the present invention is directed to an imaging apparatus including a printhead carrier, a printhead mounted to the printhead carrier, and a printhead maintenance station including a printhead maintenance cap and a moving mechanism coupled to the printhead maintenance cap for moving the printhead maintenance cap relative to the printhead. The printhead maintenance cap includes a wall portion having a proximal end and a distal end, the wall portion defining an interior region. A first perimetrical lip extends from the distal end of the wall portion by a first extent, the first perimetrical lip defining a primary sealing surface. A second perimetrical lip extends from the distal end of the wall portion by a second extent, the second perimetrical lip being spaced apart from the first perimetrical lip, wherein a perimetrical valley is defined between the first perimetrical lip and the second perimetrical lip.
Another advantage of the present invention is that by having two sealing lips, the chances of providing an adequate seal with the topography of the printhead is increased.
Yet another advantage is the lip that first contacts the printhead can be more compliant than the second lip, thereby potentially reducing the capping force necessary to provide an adequate seal with the topography of the printhead.